Cross Sectional Anatomy

Dr Ramachandrappa

Page 1

Relevance of Cross Sectional Anatomy in Diagnostic and Therapeutic Measures

“Man’s World has always been grounded upon his body as its center, from it and its necessities he has circled out and learned what he knows about the universe”

Introduction

Clinical anatomy is fascinating – most essential for clinicians. Anatomy is boring – most essential for surgeons. Cross sectional anatomy is informative and amusing – most essential for anatomists, radiologists, sonologists and surgeons.

The understanding of the cross sectional anatomy is basic to the proper interpretation in the various diagnostic procedures like computerized tomography, ultrasound, magnetic resonance imaging, position emission tomography , SPECT, nuclear imaging technic, as it reveals the three dimensional relationships of various structures of the body. The study of anatomy through the use of the cross section has fallen into disuse in western countries during 18th century. In our country it has rarely made its appearance in the curriculum of under graduates and post graduates or in the relevant clinical materials.

The study of anatomy of cross section even though it has begun in the 16th century it could not have its relevance either in diagnostic and therapeutic use till 1911. The ignorance of the importance of cross sectional anatomy to the eastern people may be due to under development of technology and lack of awareness of the newer imaging technics in radiology.

History

History of anatomy started in the early part of the 16th century by chamberlain, Chouland, Andreas Vesalius, Vidius, Bartholin and Graaaf. The further development was not a rapid pace due the lack of methods, which would harden the bodies. Pioneer work by the Russian anatomist and surgeon Nicolas Pirogiff during 1852 to 1858 and Legender using the method of hardening the various parts of the body in alcohol and the method of decalcifying the entire pelvis in by weak nitric acid. In the early part of 19th century De Riemer’s Dutch anatomist revived this method thereby bringing out its importance once again.

The study of cross sectional anatomy entered a new era after the introduction of formalin as a hardening substance in the 1895 by Gerota which was later modified by Terry using a solution made of equal parts 50% formalin without using any freezing techniques.

Preparation of sections and preservation of specimens

Selection of Cadaver:

Age: Middle aged individual

Bodily habitus: It should have a well developed muscular system, skeletal system. Organs should be empty at the time of section. Cause of death should not have produced gross anatomical change.

Embalming the Cadaver: The so selected cadaver is injected with embalming fluid to retain the colour of the muscle and organs.

Circumferential measurements – head, neck, thorax, abdomen and limbs.

Marking of the planes on the surface of the body.

The following plane are to be marked and photographs are to be taken.

Supra orbito meatal plane Infra orbito meatal plane – FRANKFORT’S PLANE – Plane of sternal angle Inter spinal plane The cadaver after embalming is kept for freezing for 3 days then kept in a supine position and the following sections are made into 10cms thickness.

In the head and neck region

Oblique head sections are made along the supra orbito meatal plane at 20-25 degree to the infra orbito meatal plane. Oblique head sections OH-1 to OH 10 with sections of 1 to 2 cm’s thickness are made for the study of orbit oral cavity, nasal cavity. (Enclosure IA, 2A,3A).

Neuro ocular plane defined as the computerized tomography plane passing through both lenses, optic nerve heads and optic canal in position of gaze – It includes all visual pathways starting from cornea to clacarine fissure. It would reflect orientation of the temporal horn of lateral ventricle , thus enhancing the accuracy of 3 dimensional approach in the evaluation of orbito- cephalic anatomy and diagnosis. In the neck, thorax, abdomen, pelvis, and limbs horizontal sections are made similar to above. (Enclosure II, III, IV, V, VI). After making the sections each section is covered with an x-ray film on both the surfaces and kept in a deep freezer. Then each section id washed carefully to remove the debris and frozen contents from all organs. The thin sections are kept for photographs and analytical study. The sections so made are treated with propylene glycol to prevent reflections and photographs are taken using sophisticated equipment. The specimens can be preserved for a longer duration with a so lution known as Jores II fluid (1000ml distilled water, 20 ml glycerol, 100ml potassium acetate). The sections are secured by suturing or with gelatin glue.